1. Field of the Invention
The present invention relates to a content delivering system, a server, and a content delivering method that deliver a content to a client, and more particularly to a content delivering system, a server, and a content delivering method that enable to realize a low cost and a large scale delivery of an attribute content such as an advertisement according to an attribute of a user without necessitating a network change.
2. Description of the Related Art
Recently, along with the spread of a large capacity communication line such as an asymmetric digital subscriber line (ADSL) or a fiber to the home (FTTH), Internet is increasingly used to carry out a content delivery of a moving image and the like. When using Internet to carry out the content delivery, some businesses deliver a content to a user who has carried out a paid member registration whereas some businesses insert an advertisement into the content and deliver the content to the user by using an advertisement revenue. If the content is delivered using the advertisement revenue, the user can freely view and appreciate the content that includes the inserted advertisement.
An advertisement provider who provides the advertisement expects an impact by inserting the advertisement into the content. Thus, a provider who delivers the content needs to increase an appeal of the advertisement that is inserted into the content for the user. In a technology disclosed in Japanese Patent Application Laid-open No. 2002-330416, an advertisement appropriate for an attribute of the user is inserted into the content so that the user to whom the advertisement is delivered is limited. Using the technology mentioned earlier enables to deliver the content that includes the inserted advertisement that differs according to the attribute of the user. Thus, the advertisement of a specific product or a service can be provided to the user of a particular age group or gender who is likely to be highly interested in the product or the service.
Thus, when delivering an attribute content such as the advertisement according to the attribute of the user, because a content delivering server needs to grasp the attribute of each individual user, generally unicast communication is carried out. However, in the unicast communication, a load on the server increases, thereby necessitating installation of a high performance server that can withstand the load. Further, because a network load in the vicinity of the server also increases, a network resource also needs to be strengthened, thus resulting in a significant cost for the delivery of the attribute content by using the unicast communication. To overcome the drawback, a technology is disclosed in Japanese translation of PCT international application (kohyo) No. 2002-544609 in which the users are grouped and the attribute content is delivered to multicast addresses of each group.
However, for carrying out a multicast communication to deliver the attribute content to the multicast addresses, all devices such as routers on a path, which is used to transmit the attribute content, need to be compatible with the multicast communication. Accordingly, an existing network infrastructure needs to be significantly altered. Therefore, realizing the complete multicast communication becomes difficult. Further, when carrying out the multicast communication, the attribute content cannot be delivered using a plurality of providers.